1. The Field of the Invention
The present invention relates generally to electronic circuitry. More particularly, embodiments of the present invention relate to mechanisms for using a third state applied to a digital input terminal of a circuit to initiate non-standard operational modes of the circuit.
2. Background and Relevant Art
Electronic circuitry provides great utility to a wide variety of devices and systems. A typical electronic module includes an electronic circuit protected by packaging and having a number of input/output terminals. These input/output terminals may take any form including pins, pads or the like. Surrounding circuitry may interact with the electronic module by applying and receiving signals on the input/output terminals.
Input terminals may receive signals from surrounding circuitry, and output terminals may provide signals to surrounding circuitry. Some terminals may be both input and output terminals thereby enabling bi-directional communication. Furthermore, some terminals may be configured to interact using digital signals, while others may be configured to interact using analog signals. Digital input terminals are typically configured to receive one of two binary states during normal operation.
As semiconductor processing technology has enabled smaller feature dimension sizes, the complexity of circuitry that can fit within a given die size has increased dramatically. Furthermore, as circuit complexity increases, there is a tendency for the circuit to have more input/output needs to support the increased complexity. Accordingly, the size of a given module is often limited not by the die size, but by the number of input/output terminals. In such modules, it is advantageous to reduce the number of input/output terminals as the reduction translates into the ability to reduce the module size.